Method of performing cell selection and re-selection using pmax parameters and system adapted thereto

ABSTRACT

The present disclosure relates to a communication method and system for converging a 5 th  Generation (5G) communication system for supporting higher data rates beyond a 4th Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A cell selection/re-selection method and an apparatus adapted thereto is provided. The cell selection method of a terminal includes: receiving, from a base station, first maximum power information, PEMAX1 and second maximum power information, PEMAX2, related to maximum transmission power levels of the terminal on the uplink; calculating a compensation parameter, Pcompensation, related to uplink transmission power of the terminal, using the first maximum power information and the second maximum power information; calculating a cell selection reception level value, Srxlev, using the compensation parameter; and selecting a cell based on the calculated cell selection reception level value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/677,426 filed on Nov. 7, 2019, which is a continuation of U.S. patentapplication Ser. No. 16/357,254 filed on Mar. 18, 2019 now U.S. Pat. No.10,602,435 issued on Mar. 24, 2020, which is a continuation of U.S.patent application Ser. No. 15/336,720 filed on Oct. 27, 2016 now U.S.Pat. No. 10,237,813 issued on Mar. 19, 2019, which claims priority toU.S. Provisional Patent Application No. 62/246,898 filed on Oct. 27,2015, the disclosures of which are herein incorporated by reference intheir entirety.

BACKGROUND 1. Field

The present invention relates to wireless communication systems, andmore particularly, to a method and apparatus for user equipment (UE) toperform the cell selection and re-selection, using P_(MAX) parameters.

2. Description of Related Art

In order to meet the increase in the demand for wireless data trafficafter the commercialization of 4G communication systems, considerableeffort has been made to develop pre-5G communication systems or improved5G communication systems. In order to achieve a high data transmissionrate, 5G communication systems are being developed to be implemented ina band of extremely high frequency, or millimeter wave (mmWave), e.g., aband of 60 GHz. This is one reason why ‘5G communication systems’ or‘pre-5G communication systems’ are called ‘beyond 4G networkcommunication systems’ or ‘post LTE systems.’ In order to reduce theoccurrence of stray electric waves in a band of extremely high frequencyenergy and to increase the transmission distance of electric waves in 5Gcommunication systems, various technologies being explored, for example:beamforming, massive MIMO, Full Dimensional MIMO (FD-MIMO), arrayantennas, analog beam-forming, large scale antennas, etc. In order toimprove system networks for 5G communication systems, varioustechnologies have been developed, e.g.: evolved small cell, advancedsmall cell, cloud radio access network (cloud RAN), ultra-dense network,Device to Device communication (D2D), wireless backhaul, moving network,cooperative communication, Coordinated Multi-Points (CoMP), interferencecancellation, etc. In addition, for 5G communication systems, othertechnologies have been developed, e.g., Hybrid FSK and QAM Modulation(FQAM) and Sliding Window Superposition Coding (SWSC), as AdvancedCoding Modulation (ACM), Filter Bank Multi Carrier (FBMC),non-orthogonal multiple access (NOMA), sparse code multiple access(SCMA), etc.

The Internet has evolved from a human-based connection network, wherehumans create and consume information; to the Internet of Things (IoT)where distributed configurations, such as objects, exchange informationwith each other to process the information. The technology related tothe IoT is starting to be combined with, for example, a technology forprocessing big data through connection with a cloud server, and this iscalled an Internet of Everything (IoE) technology. In order to manifestthe IoT, various technical components are required, such as, a sensingtechnology, wired/wireless communication and network infra technology, aservice interfacing technology, a security technology, etc. In recentyears, a sensor network for connecting objects, Machine to Machine(M2M), Machine Type Communication (MTC), etc. have been researched.Under the IoT environment, intelligent Internet Technology (IT) servicesmay be provided to collect and analyze data obtained from objectsconnected to each other and thus to create new value for human life. Asexisting IT technologies are fused and combined with various industries,the IoT may also be applied within various fields, such as: smart homes,smart buildings, smart cities, smart cars or connected cars, smartgrids, health care, smart home appliances, high quality medicalservices, etc.

To this end, various attempts have been made to apply 5G communicationsystems to the IoT. For example, various technologies related to sensornetworks, Machine to Machine (M2M), Machine Type Communication (MTC),etc., have been implemented by beam-forming, MIMO, array antenna, etc.,as 5G communication technology. The application of the cloud RAN as abig data processing technology described above may be an example of ahybrid of 5G technology and IoT technology.

As such, in order to meet the increase in the demand for wireless datatraffic, research has been undertaken to develop communication systemsin various technical fields. Examples of the communication systems aredevice to device (D2D) communication, a carrier aggregation system foroperating a number of cells, a multiple antenna system using large scaleantennas, etc.

SUMMARY

To address the above-discussed deficiencies, it is a primary object toprovide a method and apparatus that enables user equipment (UE) toperform the cell selection and re-selection using a number of PMAXparameters.

The present invention further provides a method and apparatus forincreasing the reliability of a Semi-Persistent Scheduling (SPS)activation signal and an SPS deactivation signal in the shared SPSoperation.

In accordance with an aspect of the present invention, a cell selectionmethod of a terminal is provided. The method includes: receiving, from abase station, first maximum power information, PEMAX1, and secondmaximum power information, PEMAX2, related to the maximum transmissionpower level of the terminal on the uplink; calculating a compensationparameter, Pcompensation, related to uplink transmission power of theterminal, using the first maximum power information and the secondmaximum power information; calculating a cell selection reception levelvalue, Srxlev, using the compensation parameter; and selecting a cellbased on the calculated cell selection reception level value.

Preferably, the first maximum power information and the second maximumpower information is contained in system information transmitted fromthe base station.

Preferably, the compensation parameter is calculated by the followingEquation 1:

Pcompensation=max(PEMAX1−PPowerClass,0)−{min(PEMAX2,PPowerClass)−min(PEMAX1,PPowerClass)}  Equation(1)

where Pcompensation denotes the compensation parameter, PEMAX1 denotesthe first maximum power information, PEMAX2 denotes the second maximumpower information, and PPowerClass denotes the maximum RF output powerof the terminal.

Preferably, the cell selection reception level value, Srxlev, iscalculated by the following Equation 2:

Srxlev=Qrxlevmeas−(Qrxlevmin+Qrxlevminoffset)−Pcompensation  Equation(2)

where Srxlev denotes cell selection reception level value, Qrxlevmeasdenotes a measured received strength value, and Qrxlevminoffset denotesa power offset value for base stations with priority.

Preferably, selecting a cell includes: periodically selecting a cell,based on the calculated cell selection reception level value, todiscover a public land mobile network (PLMN) with high priority.

Preferably, the first maximum power information is a value used by aterminal that does not support a number of frequency bands, and thesecond maximum power information corresponds to at least one of a numberof frequency bands supported by the terminal.

In accordance with another aspect of the present invention, a terminalconfigured to perform the cell selection is provided. The terminalincludes: a transceiver for performing the transmission/reception ofsignals; and a controller for: controlling the transceiver to receive,from a base station, first maximum power information, PEMAX1, and secondmaximum power information, PEMAX2, related to the maximum transmissionpower level of the terminal on the uplink; calculating a compensationparameter, Pcompensation, related to uplink transmission power of theterminal, using the first maximum power information and the secondmaximum power information; calculating a cell selection reception levelvalue, Srxlev, using the compensation parameter; and selecting a cellbased on the calculated cell selection reception level value.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, may mean toinclude, be included within, interconnect with, contain, be containedwithin, connect to or with, couple to or with, be communicable with,cooperate with, interleave, juxtapose, be proximate to, be bound to orwith, have, have a property of, or the like; and the term “controller”means any device, system or part thereof that controls at least oneoperation, such a device may be implemented in hardware, firmware orsoftware, or some combination of at least two of the same. It should benoted that the functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely.Definitions for certain words and phrases are provided throughout thispatent document, those of ordinary skill in the art should understandthat in many, if not most instances, such definitions apply to prior, aswell as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates a configuration of an LTE system according to anembodiment of the present invention;

FIG. 2 illustrates a radio protocol stack in an LTE system according toembodiments of the present invention;

FIG. 3 illustrates a flow diagram of operations between UE and eNBaccording to embodiment of the present invention;

FIG. 4 illustrates a flowchart of a method for UE to perform a cellselection or re-selection according to embodiment of the presentinvention;

FIG. 5 illustrates a configuration of UE according to embodiments of thepresent invention;

FIG. 6 illustrates a configuration of a primary eNB according toembodiments of the present invention;

FIG. 7 illustrates a flow diagram of operations between UE and eNBaccording to embodiment of the present invention;

FIG. 8 illustrates a format of a buffer status report (BSR) according toembodiment of the present invention;

FIG. 9 illustrates a flowchart of operations of UE according toembodiment of the present invention; and

FIG. 10 illustrates a flowchart of operations of an eNB according toembodiment of the present invention.

DETAILED DESCRIPTION

FIGS. 1 through 10, discussed below, and the various embodiments used todescribe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged electronic device.

Hereinafter, embodiments of the present invention are described indetail with reference to the accompanying drawings. The same referencenumbers are used throughout the drawings to refer to the same or similarparts. Detailed descriptions of well-known functions and structuresincorporated herein may be omitted to avoid obscuring the subject matterof the invention.

Although the following disclosure describes embodiments of the presentinvention based on Long Term Evolution (LTE) defined in thespecification of 3GPP, it should be understood that the subject matterof the present invention can also be applied to other communicationsystems that have similar technical backgrounds to the presentinvention. It will be also appreciated to those skilled in the art thatthe embodiments may be modified and the modifications may also beapplied to other communication systems, without departing from the scopeof the present invention.

In the following description, LTE system and carrier aggregation arebriefly explained.

FIG. 1 illustrates a configuration of an LTE system according to anembodiment of the present invention.

With reference to FIG. 1, the LTE system configures the wireless accessnetwork, including evolved Node Bs (called eNBs, Node Bs or basestations) 105, 110, 115, and 120, a mobility management entity (MME)125, and a serving-gateway (S-GW) 130. User equipment (UE) (which isalso called a terminal) 135 is connected to an external network via theeNB 105, 110, 115, or 120 and the S-GW 130.

eNBs 105 to 120 correspond to existing Node B of the Universal MobileTelecommunications System (UMTS). eNBs 105 to 120 are connected to UE135 via wireless channels, performing more complicated functions thanexisting Node B.

In an LTE system, since real-time services such as a Voice over IP(VoIP) service and all user traffic are serviced via shared channels,devices are required to collect information regarding states, such asbuffer states of UE devices, available transmission power states,channel states, etc., and to make a schedule. This task is performed viaeNBs 105 to 120.

One eNB controls a number of cells. For example, in order to implement atransmission rate of 100 Mbps, an LTE system employs orthogonalfrequency division multiplexing (OFDM) as a wireless access technologyat a bandwidth of 20 MHz. It also employs adaptive modulation & coding(AMC) to determine modulation scheme and channel coding rate, meetingwith the channel state of UE.

The S-GW 130 is an entity that provides data bearers. The S-GW 130establishes or removes data bearers according to the control of the MME125. The MME 125 manages the mobility of UE and controls a variety offunctions. The MME 125 connects to a number of ENBs.

FIG. 2 illustrates a radio protocol stack in an LTE system according toembodiments of the present invention.

With reference to FIG. 2, UE and eNB have packet data convergenceprotocol (PDCP) 205 and 240, radio link control (RLC) 210 and 235, andmedium access control (MAC) 215 and 230, respectively. PDCP 205 and 240compress/decompress the IP header. RLC 210 and 235 reconfigure PDCPpacket data unit (PDU) in proper size and perform an automatic repeatrequest (ARQ) operation.

MAC 215 and 230 connect to a number of RLC layer devices configured inone UE device. MAC 215 and 230 multiplex RLC PUDs to MAC PDU, andde-multiplex RLC PDUs from MAC PDU. Physical layers (PHY) 220 and 225 inUE and eNB channel-code and modulate data from the upper layers, createOFDM symbols, and transmit them via a wireless channel. In addition, PHY220 and 225 demodulate and channel-decode OFDM symbols transmitted via awireless channel, and transfer them to the upper layers.

In some embodiments, user equipment (UE) enables to perform the cellselection and re-selection using a number of PMAX parameters.

In LTE communication systems, the mobility of UE are divided into a typeof mobility according to an instruction of eNB and a type of mobilitythat UE determines for itself. UE controls the UE′ mobility for itselfin an idle state, i.e., performs the cell selection and cellre-selection. A process of UE to select/re-select a cell is alsoexpressed as UE camps on a corresponding cell. UE is capable ofdetermining whether it may camp on a corresponding cell, considering thedownlink signal strength, the uplink transmission power of a cell, etc.

With the development of hardware/software and the radio frequency (RF)technology of UE, UE is capable of satisfying the spectrum emissionstandard requiring a relatively large amount of transmission power. Forexample, in order to satisfy a specified emission standard, legacy UEhas used transmission power of a maximum of 17 dBm. New UE is capable ofsatisfying the emission standard using transmission power of 23 dBm.

When UE 1 maintaining a relatively low level of transmission power andUE 2 capable of using a relatively high level of transmission powercoexist in a cell in order to satisfy the emission output standard, thepresent invention is capable of applying corresponding maximum levels oftransmission power that differ from each other to the two UE devicesrespectively.

The present invention transmits, to UE, a number of levels of uplinkmaximum transmission power, P_(MAX), allowed in a cell, so that the UEselects one of the levels of P_(MAX), based on the UE's condition.

In particular, when UE: determines whether it camps on a specified cell;or detects a minimum fitness of using a neighboring cell and a servingcell in the cell re-selection (considering both the allowed uplinktransmission power and the received strength of the downlink referencesignal, which is denoted by Srxlevmin), the UE is capable of selectingpart of a number of P_(MAX) parameters. The UE is capable of camping ona proper cell based on the selected P_(MAX) parameters.

In some embodiments, following steps are included.

1. Periodic cell selection

-   -   Q_(rxlevmin,SIB1) and Pcompensation are used to calculate        Srxlev; and P_(EMAX,SIB1), P_(EMAX,SIB2), and P_(PowerClass) are        used to calculate Pcompensation; or    -   Q_(rxlevmin,SIB2) and Pcompensation are used to calculate        Srxlev; and P_(PowerClass) and one of P_(EMAX,SIB1) and        P_(EMAX,SIB2) are used to calculate Pcompensation

2-1. Determination as to whether to measure an intra-frequencynon-serving cell for the cell re-selection; or

2-2. Determination as to whether to measure an inter-frequency withequal or lower priority non-serving cell for the cell re-selection; or

2-3. In order to determine whether to perform the cell re-selection tothe inter-frequency with higher priority non-serving cell

Q_(rxlevmin,SIB1) and Pcompensation are used to calculate Srxlev of aserving cell; and P_(EMAX SIB1), P_(EMAX,SIB2), and P_(PowerClass) areused to calculate Pcompensation;

Q_(rxlevmin,SIB2) and Pcompensation are used to calculate Srxlev of aserving cell; and P_(Power Class) and one of P_(EMAX,SIB1) andP_(EMAX,SIB2) are used to calculate Pcompensation; or

Q_(rxlevmin,SIB5) and Pcompensation are used to calculate Srxlev of anon-serving cell; and P_(EMAX, SIB5) and P_(PowerClass) are used tocalculate Pcompensation

FIG. 3 illustrates a flow diagram of operations between UE and eNBaccording to embodiment of the present invention.

In a mobile communication system configured with UE 301 and eNB/cell302, UE 301 in an idle state receives system information in a cell inoperation 305. The system information may contain information regardinga number of levels of P_(MAX).

Pmax_SIB1: Pmax broadcast via SIB1. Only one Pmax_SIB1 is within onecell.

Pmax_SIB2: Pmax broadcast via SIB2. A number of Pmax_SIB2 may be withinone cell.

Pmax_SIB5: Pmax broadcast via SIB5. A number of Pmax_SIB5 may be withinone cell.

UE 301 performs the periodic cell selection, part of the processes ofsearching for a higher priority PLMN, in operation 310. In this case, UE301 calculates the use fitness (Srxlevmin) of a serving cell as in thefollowing Equation 1-1. TABLE 1 shows some parameters indicated inEquation 1-1.

Srxlev=Q _(rxlevmeas)(Q _(rxlevmin,SIB1) +Q_(rxlevminoffset))−Pcompensation  Equation 1-1

TABLE 1 Srxlev Cell selection RX level value (dB) Q_(rxlevmeas) Measuredcell RX level value (RSRP) Q_(rxlevmin, SIB1) Minimum required RX levelin the cell (dBm) Three different values are provided via SIB1, SIB3,and SIB5. A value, obtained from the equation, via SIB 1, is used.Q_(rxlevminoffset) Offset to the signalled Q_(rxlevmin) taken intoaccount in the Srxlev evaluation as a result of a periodic search for ahigher priority PLMN while camped normally in a VPLMN [23.122]P_(EMAX, SIB1) Maximum TX power level an UE may use when transmitting onthe uplink in the cell (dBm) defined as P_(EMAX) in [TS 36.101] A value,obtained via SIB 1 and used by UE that does not support multiple band.P_(EMAX, SIB2) Maximum TX power level an UE may use when transmitting onthe uplink in the cell (dBm) defined as P_(EMAX) in [TS 36.101] A numberof pairs are obtained via SIB2. One maximum per Frequency Band. UE uses,as P_(EMAX, SIB2), P_(EMAX) corresponding to a band with the highestpriority from among the bands that the UE supports P_(PowerClass)Maximum RF output power of the UE (dBm) according to the UE power classas defined in [TS 36.101]

Srxlev=Q _(rxlevmeas)−(Q _(rxlevmin,x) +Q_(rxlevminoffset))−Pcompensation  Equation 1-2

In the equation 1-2, when Q_(rxlevmin,SIB2) is not broadcast in theserving cell (or UE supports none of Q_(rxlevmin,SIB2) in the servingcell), Q_(rxlevmin,X) is Q_(rxlevmin,SIB1). When UE supports at leastone of Q_(rxlevmin,SIB2) in the serving cell, Q_(rxlevmin,X) isQ_(rxlevmin,SIB2). TABLE 2 shows a parameter indicated in Equation 1-2.

TABLE 2 Q_(rxlevmin, SIB2) Minimum required RX level in the cell (dBm).A number of pairs are obtained via SIB2. One maximum per Frequency Band.UE uses, as P_(EMAX, SIB2), Qrxlevmin, SIB2 corresponding to a band withthe highest priority from among the bands that the UE supports

Pcompensation=max(P _(EMAX,SIB1) −P _(PowerClass),0)−[min(P _(EMAX,SIB2),P _(PowerClass))−min

(P _(EMAX,SIB1) ,P _(PowerClass))]  Equation 2-1

In the equation 2-1, when P_(EMAX,SIB2) is not broadcast in the servingcell (or UE does not support none of P_(EMAX,SIB2) in the serving cell),P_(EMAX,SIB2) is 0.

Pcompensation=max(P _(EMAX,X) −P _(PowerClass),0)  Equation 2-2

In the equation 2-2, when P_(EMAX,SIB2) is not broadcast in the servingcell (or UE does not support none of P_(EMAX,SIB2) in the serving cell),P_(EMAX,X) is P_(EMAX,SIB1). When UE supports at least one ofP_(EMAX,SIB2) in the serving cell, P_(EMAX,X) is P_(EMAX,SIB2).

In the periodic cell selection, Equations 1-1 and 2-1 or Equations 1-2and 2-2 are used to calculate the cell fitness.

In some embodiments of Equation 2-1, Pcompensation is negative in a cellwhere P_(PowerClass)>P_(EMAX,SIB2), and a relatively high

-   -   level of cell fitness for the same Qrxlevmeas is calculated,        thereby resulting in the extension of coverage, Pcompensation is        negative in a cell where        P_(EMAX,SIB2)>P_(PowerClass)>P_(EMAX,SIB1),    -   resulting in the extension of coverage. The extent of the        extension of coverage is less than that of the first case        described above, and Pcompensation is positive when        P_(PowerClass)<P_(EMAX, SIB1), thereby resulting in the        reduction of coverage.

When Srxlev of a serving cell is greater than ‘0’ and Squal is greaterthan ‘0,’ the UE 301 considers the serving cell to be a selectable cell.When there is a PLMN cell satisfying the conditions from among PLMNcells with higher priority, the UE selects the cell.

The UE 301 is capable of measuring intra-frequency neighboring cells toperform the cell re-selection, while performing the periodic cellselection, in operation 315. When the UE 301 ascertains that thefollowing condition is satisfied, it is capable of measuring theintra-frequency neighboring cells.

When the serving cell satisfies the conditions, Srxlev>S_(IntraSearchP)and Squal>S_(IntraSearchQ), the UE 301 may choose not to perform themeasurement of intra-frequency neighboring cells.

Otherwise, the UE may perform the measurement of intra-frequencyneighboring cells. S_(IntraSearchP) and S_(IntraSearchQ) are providedvia system information of a serving cell. The UE 301 calculates Srxlevof a serving cell by using either Equations 3-1 and 2-1 or Equations 3-2and 2-2 as follows:

Srxlev=Q _(rxlevmeas) −Q _(rxlevmin,SIB1) −Pcompensation  Equation 3-1

Srxlev=Q _(rxlevmeas) −Q _(rxlevmin,SIB2) −Pcompensation  Equation 3-2

The UE 301 is capable of performing the inter-frequency measurement forthe cell re-selection. The inter-frequency measurement by the UE 301 iscontrolled by the cell re-selection priority (also called the priority).

With respect to a frequency with a priority higher than that of acurrent serving cell/frequency, the UE 301 performs the periodicmeasurement for neighboring cells. On the other hand, with respect to afrequency with a priority less than or equal to that of a currentserving cell/frequency, the UE 301 performs the measurement forneighboring cells only when a specified condition is satisfied.

More specifically, the UE 301 determines whether the UE 301 measuresneighboring cells whose frequency has a priority less than or equal tothat of a serving cell/frequency, based on the following conditions inoperation 320.

If the serving cell fulfils Srxlev>S_(nonIntraSearchP) andSqual>S_(nonIntraSearchQ), the UE may choose not to perform measurementsof E-UTRAN inter-frequencies or inter-RAT frequency cells of equal orlower priority.

Otherwise, the UE shall perform measurements of E-UTRANinter-frequencies or inter-RAT frequency cells of equal or lowerpriority according to [10].

The UE 301 calculates Srxlev of a serving cell by using either Equations3-1 and 2-1 or Equations 3-2 and Equation 2-2.

When the UE 301 ascertains that a cell re-selection condition issatisfied from the neighboring cell measurement result, the UE 301re-selects a new cell. When the UE 301 ascertains that the followingcondition is satisfied, the UE 301 re-selects a neighboring cell with ahigher priority in operation 325. The cell re-selection to a cell on ahigher priority E-UTRAN frequency or inter-RAT frequency than theserving frequency shall be performed if:

A cell of a higher priority RAT/frequency fulfilsSrxlev>Thresh_(X,HighP) during a time interval Tre-selection_(RAT); and

-   -   More than 1 second has elapsed since the UE camped on the        current serving cell.

The UE 301 calculates Srxlev of a neighboring cell under the conditions,by using Equations 4-1 and 5-1 as follows:

Srxlev=Q _(rxlevmeas) −Q _(rxlevmin,SIB5) −Pcompensation  Equation 4-1

Pcompensation=max(P _(EMAX,SIB5) −P _(PowerClass),0)  Equation 5-1

P_(EMAX,SIB5) is values each of which is signalled per frequency viaSIB5. When P_(EMAX,SIB5) is not signalled for a frequency, UE usesP_(PowerClass) as P_(EMAX,SIB5) of the frequency.

When the UE 301 ascertains that the following condition is satisfied,the UE 301 re-selects a cell with a priority less than or equal to thatof a serving cell/frequency in operation 330.

The serving cell fulfils Srxlev<Thresh_(Serving, LowP) and a cell of alower priority RAT/frequency fulfils Srxlev>Thresh_(X,LowP) during atime interval Treslection_(RAT); and

More than 1 second has elapsed since the UE camped on the currentserving cell.

The UE 301 calculates Srxlev of a neighboring cell by using Equations4-1 and 5-1, and also Srxlev of a serving cell by using either Equations3-1 and 2-1 or Equations 3-2 and 2-2.

FIG. 4 illustrates a flowchart of a method for UE to perform the cellselection or re-selection according to embodiment of the presentinvention.

A UE is powered on and performs the cell selection in operation 405.

When the UE has stored valid system information, the UE performs thestored information cell selection. Otherwise, the UE performs theinitial cell selection.

In the initial cell selection, the UE calculates Srxlev by usingEquation 6 as follows.

Srxlev=Qrxlevmeas−Qrxlevmin,ini  Equation (6)

Qrxlevmin,ini is a value defined in the specification. It is used whenthe UE does not obtain system information regarding a correspondingcell.

In the stored information cell selection, the UE calculates Srxlev byusing either Equations 1-1 and 2-1 or Equations 1-2 and 2-2.

The UE selects a cell whose Srxlev and Squal are greater than or equalto ‘0,’ and camps on the cell.

The UE receives system information regarding the selected cell, andobtains the following parameters in operation 410.

One P_(EMAX, SIB1), n P_(EMAX,SIB2), one P_(EMAX, SIB3), mP_(EMAX, SIB5), one Q_(rxlevmin,SIB1), n Q_(rxlevmin,SIB2), oneQ_(rxlevmin,SIB3) and m Q_(rxlevmin,SIB5), where m and n are positiveintegers.

n is related to the number of frequency bands supported by acorresponding serving cell. When the number of frequency bands supportedby a corresponding serving cell is n′, n and n′ has a relationship,n<n′.

m is related to the number of inter-frequency bands provided via SIB5.When the number of inter-frequency bands provided via SIB5 is m′, m andm′ has a relationship, m≤m′.

The UE determines whether the UE measures neighbouring cells of the samefrequency, considering Srxlev of a current serving cell in operation415. UE calculates Srxlev of a serving cell by using either Equations3-1 and 2-1 or Equations 3-2 and 2-2.

The UE determines whether the UE searches for neighboring cells ofanother frequency in operation 420. The other frequency means not allfrequencies except for the current frequency but only a frequency thatis related to information provided via SIB5.

The UE performs the periodic measurement for frequencies with a priorityhigher than that of the current frequency. UE determines whether the UEperforms the measurement for frequencies with a priority less than orequal to that of the current frequency, considering Srxlev of a servingcell.

The UE calculates Srxlev of a serving cell by using either Equations 3-1and 2-1 or Equations 3-2 and 2-2.

When the UE ascertains that a specified condition is satisfied, the UEre-selects a new cell in operation 425. When UE re-selects a cell withhigh priority, the UE calculates Srxlev of neighboring cells by usingEquations 4-1 and 5-1.

When the UE re-selects a cell with priority less than or equal to thatof a serving cell/frequency, the UE calculates Srxlev of neighboringcells by using Equations 4-1 and 5-1, and Srxlev of a serving cell byusing either Equations 3-1 and 2-1 or Equations 3-2 and 2-2.

Using Equations 1-1 and 2-1 to calculate Srxlev of a serving cell meansthat: Srxlev of a serving cell is calculated by using Q_(rxlevmin,SIB1)and Pcompensation; and Pcompensation is calculated by usingP_(EMAX, SIB1), P_(EMAX,SIB2), and P_(PowerClass).

Using Equations 1-2 and 2-2 to calculate Srxlev of a serving cell meansthat: Srxlev of a serving cell is calculated by using Pcompensation andeither Q_(rxlevmin,SIB2) or Q_(rxlevmin,SIB1); and Pcompensation iscalculated by using P_(PowerClass) and either P_(EMAX, SIB1) orP_(EMAX,SIB2).

Using Equations 3-1 and 2-1 to calculate Srxlev of a serving cell meansthat: Srxlev of a serving cell is calculated by using Q_(rxlevmin,SIB1)and Pcompensation; and Pcompensation is calculated by usingP_(EMAX, SIB1), P_(EMAX,SIB2), and P_(PowerClass).

Using Equations 3-2 and 2-2 to calculate Srxlev of a serving cell meansthat: Srxlev of a serving cell is calculated by using Q_(rxlevmin,SIB2)and Pcompensation; and Pcompensation is calculated by usingP_(PowerClass) and either P_(EMAX, SIB1) or P_(EMAX,SIB2).

Using Equations 4-1 and 5-1 to calculate Srxlev of a neighboring cellmeans that: Srxlev of a corresponding cell is calculated by usingQ_(rxlevmin,SIB5) and Pcompensation; and Pcompensation is calculated byusing P_(EMAX, SIB5) and P_(PowerClass).

FIG. 5 illustrates a configuration of UE according to embodiments of thepresent invention.

With reference to FIG. 5, UE includes a Radio Frequency (RF) interface510, a baseband interface 520, a storage 530, and a controller 540.

The RF interface 510 performs functions relates to thetransmission/reception of signals via a wireless channel, e.g., theconversion of frequency band, the amplification, etc. The RF interface510 up-converts baseband signals output from the baseband interface 520into RF band signals and transmits the RF signals via an antenna. The RFinterface 510 down-converts RF band signals received via the antennainto baseband signals.

The RF interface 510 is capable of including a transmission filter, areception filter, an amplifier, a mixer, an oscillator, a digital toanalog convertor (DAC), an analog to digital convertor (ADC), etc.

Although the embodiment is shown in FIG. 5 so that UE includes only oneantenna, it should be understood that the UE may be implemented toinclude a number of antennas. The RF interface 510 may also beimplemented to include a number of RF chains. The RF interface 510 iscapable of performing a beamforming operation.

In order to perform a beamforming function, the RF interface 510 iscapable of adjusting the phase and amplitude of individual signalstransmitted/received via a number of antennas or antenna elements. TheRF interface 510 is capable of performing MIMO and receiving a number oflayers in MIMO.

The baseband interface 520 performs the conversion between basebandsignals and bitstream according to a physical layer rule of the system.For example, in data transmission, the baseband interface 520 encodesand modulates a transmission bitstream, thereby creating complexsymbols.

In the data reception, the baseband interface 520 demodulates anddecodes baseband signals output from the RF interface 510, therebyrestoring a reception bitstream. For example, in data transmissionaccording to the orthogonal frequency division multiplexing (OFDM), thebaseband interface 520 encodes and modulates a transmission bitstream tocreate complex symbols, maps the complex symbols to sub-carriers, andconfigures OFDM symbols through the inverse fast Fourier transform(IFFT) operation and the cyclic prefix (CP) insertion.

In the data reception, the baseband interface 520 splits basebandsignals output from the RF interface 510 into OFDM symbol units,restores signals mapped to sub-carriers through the fast Fouriertransform (FFT) operation, and then restores a reception bitstreamthrough the demodulation and decoding operation.

The baseband interface 520 and the RF interface 510 perform thetransmission and reception of signals as described above. Accordingly,the baseband interface 520 and the RF interface 510 may also be called atransmitter, a receiver, a transceiver, a communication interface, etc.

In addition, the baseband interface 520 and/or the RF interface 510 mayinclude a number of communication modules to support wireless accesstechnologies that differ from each other. Alternatively, the basebandinterface 520 and/or the RF interface 510 may include differentcommunication modules to process signals of different frequency bands.

Examples of the wireless access technologies are: wireless LAN (e.g.,IEEE 802.11), a cellular network (e.g., LTE), etc. Examples of thedifferent frequency bands are: super high frequency (SHF) (e.g., 2.5 GHzband, 5 GHz band, etc.), millimeter wave (mmW) (e.g., 60 GHz band), etc.

The storage 530 stores a default program for operating the UE,applications, settings, data, etc. In particular, the storage 530 iscapable of storing information related to a second access node whichperforms wireless communication using a second wireless accesstechnology. The storage 530 provides the stored data according to therequest of the controller 540.

The controller 540 controls all operations of the UE. For example, thecontroller 540 controls the baseband interface 520 and the RF interface510 to perform the transmission/reception of signals. The controller 540controls the storage 540 to store/read data therein/therefrom. thecontroller 540 may be a circuit, an application-specific integratedcircuit or at least one processor.

To this end, the controller 540 is capable of including at least oneprocessor. For example, the controller 540 is capable of including acommunication processor (CP) for controlling the communication and anapplication processor (AP) for controlling upper layers such asapplications. According to embodiments of the present invention, thecontroller 540 is capable of controlling the UE to perform the functionsand the procedure described above referring to FIGS. 3 and 4.

FIG. 6 illustrates a configuration of a primary eNB according toembodiments of the present invention.

As shown in FIG. 6, the eNB includes an RF interface 610, a basebandinterface 620, a backhaul communication interface 630, a storage 640,and a controller 650.

The RF interface 610 performs functions related to thetransmission/reception of signals via a wireless channel, e.g., theconversion of frequency band, the amplification, etc. The RF interface610 up-converts baseband signals output from the baseband interface 620into RF band signals and transmits the RF signals via an antenna. The RFinterface 610 down-converts RF band signals received via the antennainto baseband signals.

The RF interface 610 is capable of including a transmission filter, areception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC,etc. Although the embodiment is shown in FIG. 6 so that the embodimentincludes only one antenna, it should be understood that the first accessnode may be implemented to include a number of antennas.

The RF interface 610 may also be implemented to include a number of RFchains. The RF processing unit 610 is capable of performing abeamforming operation. In order to perform a beamforming function, theRF interface 610 is capable of adjusting the phase and amplitude ofindividual signals transmitted/received via a number of antennas orantenna elements. The RF interface 610 is capable of transmitting one ormore layers, thereby performing the downlink MIMO function.

The baseband interface 620 performs the conversion between basebandsignals and bitstream according to a physical layer rule of a firstwireless access technology. For example, in the data transmission, thebaseband interface 620 encodes and modulates a transmission bitstream,thereby creating complex symbols.

In the data reception, the baseband interface 620 demodulates anddecodes baseband signals output from the RF interface 610, therebyrestoring a reception bitstream. For example, in the data transmissionaccording to the orthogonal frequency division multiplexing (OFDM), thebaseband interface 620 encodes and modulates a transmission bitstream tocreate complex symbols, maps the created complex symbols tosub-carriers, and configures OFDM symbols through the inverse fastFourier transform (IFFT) operation and the cyclic prefix (CP) insertion.

In the data reception, the baseband interface 620 splits basebandsignals output from the RF interface 610 into OFDM symbol units,restores signals mapped to sub-carriers through the fast Fouriertransform (FFT) operation, and then restores a reception bitstreamthrough the demodulation and decoding operation. The baseband interface620 and the RF interface 610 perform the transmission and reception ofsignals as described above. Accordingly, the baseband interface 620 andthe RF interface 610 may also be called a transmitter, a receiver, atransceiver, a communication interface, a wireless communicationinterface, etc.

The backhaul communication interface 630 provides interfaces tocommunicate with other nodes in the network. That is, the backhaulcommunication interface 630 converts: a bitstream into a physical signalto be transmitted to other nodes of the primary eNB, e.g., an auxiliaryeNB, a core network, etc.; and a physical signal from the other nodesinto a bitstream.

The storage 640 stores a default program for operating the primary eNB,applications, settings, data, etc. In particular, the storage 640 iscapable of storing information regarding a bearer allocated to theconnected UE, a measurement result reported from the connected UE, etc.The storage 640 is capable of providing the dual connectivity functionto UE or storing information to determine whether to terminate the dualconnectivity operation. The storage 640 provides the stored dataaccording to the request of the controller 650.

The controller 650 controls all operations of the primary eNB. Forexample, the controller 650 controls the baseband interface 620, the RFinterface 610 and the backhaul communication interface 630 to performthe transmission/reception of signals. The controller 650 controls thestorage 640 to store/read data therein/therefrom. To this end, thecontroller 650 is capable of including at least one processor.

The controller 650 is capable of including a dual connectivitycontroller 652 which provides UE with a dual connectivity function. Forexample, the controller 650 is capable of controlling the primary eNB toperform the functions and procedure described above referring to FIG. 3.

In some embodiments, the reliability of a Semi-Persistent Scheduling(SPS) activation signal and an SPS deactivation signal in the shared SPSoperation are increased.

In such embodiments, a UE enables to receive a signal for activating orreleasing a shared SPS to transmit, to the eNB, a regular BSR for theACK/NACK signaling in response to the received signal.

With the evolution of mobile communication systems, the minimization ofthe uplink delay has become as an important issue. The present inventionprovides a shared SPS scheme for reducing the uplink relay.

Most of the uplink delay is caused in processes where the UE requeststhe allocation of a transmission resource and the transmission resourceis allocated. In a state where the UE is successively allocated an SPStransmission resource, when data is created, the UE is capable ofperforming the rapid transmission of the data. However, when SPStransmission resources are dedicatedly allocated to all UE devices, thetransmission resources are excessively consumed.

In order to resolve the problem, the present invention introduces ashared SPS scheme that allocates the same SPS transmission resource to anumber of UE devices. UE devices configured with shared SPS perform thetransmission of data only when the UE devices have the data to betransmitted. UE devices configured with shared SPS monitor PDCCH andapply different UE identifiers to the uplink scrambling, so that the eNBcan identify uplink data from UE devices, respectively.

Since the shared SPS scheme uses only a small part of the givenresources, it is preferable that the scheme is applied to a small cellabundant in transmission resources. Therefore, the shared SPS scheme isused for a serving cell specified by an eNB, unlike general SPS schemes.

The SPS is configured via RRC, and then activated or deactivated byusing PDCCH. That is, when UE receives ‘0’ for the NDI value, along withSPS C-RNTI provided via RRC, the UE considers SPS to be activated. Onthe other hand, when a pre-defined value, e.g., all values, are set to‘0,’ along with SPS C-RNTI, UE considers SPS to be deactivated.

Alternatively, the SPS may also be deactivated by an implicit release.The implicit release refers to a scheme that enables UE to release theconfigured uplink grant when the transmission of MAC PDU without MAC SDU(hereafter called ‘Zero MAC SDU MAC PDU’) is performed successively anumber of times, n, via an SPS transmission resource. The implicitrelease is introduced to provide against the loss of SPS releasesignals.

However, when a shared SPS is applied, the implicit release needs to beignored. This is because, when there is no data to be transmitted, MACPDU without including MAC SDU needs not to be transmitted via a sharedSPS resource, so that another UE can use the shared SPS resource.

In some embodiments, when UE receives an RRCConnectionReconfigurationmessage, using IE defined in the form of ENUMERATED {SETUP}, namedSkipUplinkTX, and SkipUplinkTX, indicated by SETUP, is contained insps-ConfigUL or MAC-MainConfig of the receivedRRCConnectionReconfiguration message, the UE ignores the implicitrelease.

When the shared SPS is activated or deactivated, the shared SPS schemehas a problem where the shared SPS scheme does not check whether UEcorrectly has received the activation (deactivation) signal.

An existing SPS technology uses HARQ ACK/NACK; however, the shared SPSscheme does not uses HARQ ACK/NACK since SPS C-RNTI for the monitoringis an identifier commonly applied to a number of UE devices. Therefore,an additional device that differs from existing devices is required toincrease the reception reliability of an activation (deactivation)signal.

In some embodiments, when activating/deactivating a shared SPS, thetransmission of regular buffer status report (BSR) to check whether UEhas correctly received the activation (deactivation) signal isperformed. The BSR is used to report an amount of data that UE needs totransmit to the eNB. When a BSR satisfies one of the followingconditions, the BSR is reported to an eNB.

A buffer status report (BSR) shall be triggered if any of the followingevents occur:

-   -   UL data, for a logical channel which belongs to a LCG, becomes        available for transmission in the RLC entity or in the PDCP        entity (the definition of what data shall be considered as        available for transmission is specified in [3] and [4]        respectively) and either the data belongs to a logical channel        with higher priority than the priorities of the logical channels        which belong to any LCG and for which data is already available        for transmission, or there is no data available for transmission        for any of the logical channels which belong to a LCG, in which        case the BSR is referred below to as “Regular BSR”;    -   UL resources are allocated and number of padding bits is equal        to or larger than the size of the Buffer Status Report MAC        control element plus subheader, in which case the BSR is        referred below to as “Padding BSR”;    -   rebcBSR-Timer expires and the MAC entity has data available for        transmission for any of the logical channels which belong to a        LCG, in which case the BSR is referred below to as “Regular        BSR”;    -   periodicBSR-Timer expires, in which case the BSR is referred        below to as “Periodic BSR”.

FIG. 7 illustrates a flow diagram of operations between UE and eNBaccording to embodiment of the present invention.

With reference to FIG. 7, a mobile communication system includes UE 705,an eNB 710 and nodes. The UE 705 establishes RRC connection with the eNB710 in operation 715.

Establishing RRC connection between UE 705 and the eNB 710 means astate/condition where a Signaling Radio Bearer (SRB) is configuredbetween the UE 705 and the eNB 710 so that the UE 705 and eNB 710 cantransmit/receive RRC control messages to each other.

The RRC connection is established via a random access process in such away that: UE 705 transmits an RRC connection establishment requestmessage to the eNB 710; the eNB 710 transmits an RRC connectionestablishment message to the UE 705; and the UE 705 transmits an RRCconnection establishment complete message to the eNB 710.

After establishing the RRC connection, the eNB 710 is capable oftransmitting, to the UE 705, a control message, UECapabilityEnquiry,instructing UE to report the UE capability, if the UE capability isnecessary, in operation 720. The control message contains the field of aradio access technology (RAT) type, indicating a capability regarding anRAT, from among the capabilities of UE. When the eNB 710 receives areport of a capability regarding EUTRA, the eNB 710 sets the RAT Type toEUTRA.

When the UE 705 receives the UECapabilityEnquiry message where the RATType is set to EUTRA, the UE transmits, to the eNB 710, a controlmessage, UECapabilityInformation, containing the UE's capability forEUTRA in operation 725.

The control message contains UE-EUTRA-Capability. TheUE-EUTRA-Capability contains a name list of features supported by UE,categories of UE (ue-Category), a combination of frequency bandssupported by UE (supportedBandCombination), etc. UE supports a sharedSPS function and has completed the inter-Operability Test for thefunction. The control message may contain IE representing that UEsupports a shared SPS function.

When the eNB 710 ascertains that the latency reduction needs to beapplied to the UE 705, it is capable of instructing the UE 705 toperform the RRC connection reconfiguration in operation 730. The eNB 710is capable of transmitting the shared SPS configuration information tothe UE 705, via the RRC connection reconfiguration message. The sharedSPS configuration information is formed with SPS-Config information andSPS-Config-ext.

Alternatively, in order to configure a shared SPS, Config-ext may becontained in the lower level information of sps-ConfigUL orMAC-MainConfig of an RRCConnectionReconfiguration message. TheSkipUplinkTX may be contained in the lower level information ofsps-ConfigUL or MAC-MainConfig or SPS-Config-ext.

The structure of the SPS-Config is as follows.

SPS-Config ::= SEQUENCE { semiPersistSchedC-RNTI C-RNTI OPTIONAL, --Need OR sps-ConfigDL SPS-ConfigDL OPTIONAL, -- Need ON sps-ConfigULSPS-ConfigUL OPTIONAL -- Need ON } ... SPS-ConfigUL ::= CHOICE { releaseNULL, setup SEQUENCE { semiPersistSchedIntervalUL ENUMERATED { sf10,sf20, sf32, sf40, sf64, sf80, sf128, sf160, sf320, sf640, spare6,spare5, spare4, spare3, spare2, spare1}, implicitReleaseAfter ENUMERATED{e2, e3, e4, e8}, p0-Persi stent SEQUENCE {  p0-NominalPUSCH-PersistentINTEGER (−126...24),  p0-UE-PUSCH-Persistent INTEGER (−8..7) } OPTIONAL,-- Need OP twoIntervalsConfig ENUMERATED {true} OPTIONAL, -- Cond TDD..., [[ p0-PersistentSubframeSet2-r12 CHOICE { release NULL, setupSEQUENCE { p0-NominalPUSCH-PersistentSubframeSet2-r12 INTEGER(−126..24), p0-UE-PUSCH-PersistentSubframeSet2-r12 INTEGER (−8..7) }  }OPTIONAL -- Need ON ]] } } N1PUCCH-AN-PersistentList ::= SEQUENCE (SIZE(1..4)) OF INTEGER (0..2047) -- ASN1ST0P

SPS-Config field descriptions implicitReleaseAfter Number of emptytransmissions before implicit release, see TS 36.321 [6, 5.10.2], Valuee2 corresponds to 2 transmissions, e3 corresponds to 3 transmissions andso on. n1PUCCH-AN-PersistentList, n1PUCCH-AN-PersistentListP1 List ofparameter: n_(PUCCH) ^((1, p)) for antenna port P0 and for antenna portP1 respectively, see TS 36.213 [23, 10.1], Fieldn1-PUCCH-AN-PersistentListP1 is applicable only if thetwoAntennaPortActivatedPUCCH-Format1a1b in PUCCH-ConfigDedicated-v1020is set to true. Otherwise the field is not configured.numberOfConfSPS-Processes The number of configured HARQ processes forSemi-Persistent Scheduling, see TS 36.321 [6].p0-NominalPUSCH-Persistent Parameter: P_(O) _(—) _(NOMINAL) _(—)_(PUSCH) ₍₀₎ . See TS 36.213 [23, 5.1.1.1], unit dBm step 1. This fieldis applicable for persistent scheduling, only. If choice setup is usedand p0-Persistent is absent, apply the value of p0-NominalPUSCH forp0-NominalPUSCH-Persistent. If uplink power control subframe sets areconfigured by tpc-SubframeSet, this field applies for uplink powercontrol subframe set 1. p0-NominalPUSCH-PersistentSubframeSet2Parameter: P_(O) _(—) _(NOMINAL) _(—) _(PUSCH) ₍₀₎ . See TS 36.213 [23,5.1.1.1], unit dBm step 1. This field is applicable for persistentscheduling, only. If p0-PersistentSubframeSet2-r12 is not configured,apply the value of p0-NominalPUSCH-SubframeSet2-r12 forp0-NominalPUSCH-PersistentSubframeSet2. E-UTRAN configures this fieldonly if uplink power control subframe sets are configured bytpc-SubframeSet, in which case this field applies for uplink powercontrol subframe set 2. p0-UE-PUSCH-Persistent Parameter: P_(O) _(—)_(UE) _(—) _(PUSCH) ₍₀₎ . See TS 36.213 [23, 5.1.1.1], unit dB. Thisfield is applicable for persistent scheduling, only. If choice setup isused and p0-Persistent is absent, apply the value of p0-UE-PUSCH forp0-UE-PUSCH-Persistent. If uplink power control subframe sets areconfigured by tpc-SubframeSet, this field applies for uplink powercontrol subframe set 1. p0-UE-PUSCH-PersistentSubframeSet2 Parameter:P_(O) _(—) _(UE) _(—) _(PUSCH) ₍₀₎ . See TS 36.213 [23, 5.1.1.1], unitdB. This field is applicable for persistent scheduling, only. Ifp0-PersistentSubframeSet2-r12 is not configured, apply the value ofp0-UE-PUSCH-SubframeSet2 for p0-UE-PUSCH-PersistentSubframeSet2. E-UTRANconfigures this field only if uplink power control subframe sets areconfigured by tpc-SubframeSet, in which case this field applies foruplink power control subframe set 2. semiPersistSchedC-RNTISemi-persistent Scheduling C-RNTI, see TS 36.321 [6].semiPersistSchedIntervalDL Semi-persistent scheduling interval indownlink, see TS 36.321 [6]. Value in number of sub-frames. Value sf10corresponds to 10 sub-frames, sf20 corresponds to 20 sub-frames and soon. For TDD, the UE shall round this parameter down to the nearestinteger (of 10 sub-frames), e.g. sf10 corresponds to 10 sub-frames, sf32corresponds to 30 sub-frames, sf128 corresponds to 120 sub-frames.semiPersistSchedIntervalUL Semi-persistent scheduling interval inuplink, see TS 36.321 [6]. Value in number of sub-frames. Value sf10corresponds to 10 sub-frames, sf20 corresponds to 20 sub-frames and soon. For TDD, the UE shall round this parameter down to the nearestinteger (of 10 sub-frames), e.g. sf10 corresponds to 10 sub-frames, sf32corresponds to 30 sub-frames, sf128 corresponds to 120 sub-frames.twoIntervalsConfig Trigger of two-intervals-Semi-Persistent Schedulingin uplink. See TS 36.321 [6, 5.10], If this field is present,two-intervals-SPS is enabled for uplink. Otherwise, two-intervals-SPS isdisabled.

Conditional presence Explanation TDD This field is optional present forTDD, need OR; it is not present for FDD and the UE shall delete anyexisting value for this field.

The structure of the SPS-Config-ext is as follows.

SPS-Config-ext ::= SEQUENCE { semiPersistSchedC-RNTI2 C-RNTI OPTIONAL,semiPersistSchedIntervalUL2 ENUMERATED { sf1, sf2, sf4, sf6, sf8,spare3, spare2, spare1}, logicalChannelldList ... SharedSPSenabledCellServCellIndex } ...

In summary, SPS-config is formed with the following IEs:

First SPS C-RNTI (semiPersistSchedC-RNTI) First interval(semiPersistSchedIntervalUL) Automatic release parameter(semiPersistSchedC-RNTI)

SPS-Config-ext is formed with the following IEs:

Shared SPS indicator (SPS-Config-ext may serve as a shared SPS indicatoror an additional indicator may be used)

Second SPS C-RNTI (semiPersistSchedC-RNTI2)

Second interval (semiPersistSchedIntervalUL2)

Logical channel list (logicalChannelIdList): a name list of logicalchannels capable of using a shared SPS

serving cell id (SharedSPSenabledCell): an identifier of a serving cellwhere a shared SPS is activated/employed

SkipUplinkTX: Implicit release is ignored when indicated by SETUP. (Acorresponding IE may serve as a shared SPS indicator)

The UE 705 monitors whether the SPS function is activated in operation735. The UE 705 monitors whether a general SPS and a shared SPS areactivated, respectively.

Setting a general SPS function to a UE device means that: onlySPS-config is set to UE at a corresponding timing but SPS-config-ext isnot set thereto. In this case, the UE has received anrrcConnectionReconfiguration message containing valid SPS-config fromthe eNB. The UE has not released the received SPS-config. The UE has notreceived the SPS-Config-ext. Although the UE received theSPS-Config-ext, the UE has already released the SPS-Config-ext. Forexample, when UE, not set with an SPS, receives anrrcConnectionReconfiguration control message that contains onlySPS-config but does not contain SPS-Config-ext,rrcConnectionReconfiguration control message is set with a general SPS.

Setting a shared SPS function to a UE device means that: SPS-config andSPS-config-ext are set to UE at a corresponding timing. In this case,the UE has received an rrcConnectionReconfiguration message containingvalid SPS-config and valid SPS-Config-ext from the eNB. The UE has notreleased the received SPS-config and the received SPS-Config-ext.

For example, when a UE, not set with an SPS, receives anrrcConnectionReconfiguration control message wherein SPS-config andSPS-Config-ext are contained, it means that the UE has been set with ashared SPS.

A UE sets with a general SPS monitors PDCCH of PCell or PSCell(hereafter called SpCell) and determines whether SPS is activated. Whenthe UE receives uplink grant through a first SPS C-RNTI via the PDCCH ofSpCell, the UE monitors a new data indicator (NDI) of the uplink grant.When the NDI is ‘0’ and information regarding the PDCCH is notinformation specifying the release, the UE stores the uplink grant andthe associated HARQ information as configured uplink grant and initiatesthe SPS operation.

-   -   else, if this Serving Cell is the SpCell and if an uplink grant        for this TTI has been received for the SpCell on the PDCCH of        the SpCell for the MAC entity's Semi-Persistent Scheduling        C-RNTI:    -   if the NDI in the received HARQ information is 1:    -   consider the NDI for the corresponding HARQ process not to have        been toggled;    -   deliver the uplink grant and the associated HARQ information to        the HARQ entity for this TTI.    -   else if the NDI in the received HARQ information is 0:    -   if PDCCH contents indicate SPS release:    -   clear the configured uplink grant (if any).    -   else:    -   store the uplink grant and the associated HARQ information as        configured uplink grant;    -   initialize (if not active) or re-initialize (if already active)        the configured uplink grant to start in this TTI and to recur        according to rules in subclause 5.10.2 (according to        semiPersistSchedIntervalUL);    -   consider the NDI bit for the corresponding HARQ process to have        been toggled;    -   deliver the configured uplink grant and the associated HARQ        information to the HARQ entity for this TTI.

HARQ information: HARQ information for DL-SCH or for UL-SCHtransmissions consists of New Data Indicator (NDI), Transport Block (TB)size. For DL-SCH transmissions the HARQ information also includes HARQprocess ID. For UL-SCH transmission the HARQ information also includesRedundancy Version (RV). In case of spatial multiplexing on DL-SCH theHARQ information comprises a set of NDI and TB size for each transportblock. HARQ information for SL-SCH and SL-DCH transmissions consists ofTB size only.

Via a PDCCH of a serving cell specified as SharedSPSenabledCell; or viaa PDCCH of a scheduling cell of the serving cell (refer to the cellCrossCarrierSchedulingConfig which provides scheduling informationregarding the serving cell) in a state where the cross-carrierscheduling is employed, when UE set with a shared SPS receives uplinkgrant through an SPS C-RNTI, the UE monitors an NDI of the uplink grant.When the NDI is ‘0’ and information regarding the PDCCH is notinformation specifying the release, UE stores the uplink grant and theassociated HARQ information as configured uplink grant and initiates theshared SPS operation.

The SPS C-RNTI for the monitoring may be first SPS C-RNTI or second SPSC-RNTI. The following operations are explained, assuming the second SPSC-RNTI.

-   -   else, if this Serving Cell is the SharedSPSenabledCell and if an        uplink grant for this TTI has been received for the        SharedSPSenabledCell on the PDCCH of the SharedSPSenabledCell        for the MAC entity's Semi-Persistent Scheduling C-RNTI2:    -   if the NDI in the received HARQ information is 1:    -   consider the NDI for the corresponding HARQ process not to have        been toggled;    -   deliver the uplink grant and the associated HARQ information to        the HARQ entity for this TTI.    -   else if the NDI in the received HARQ information is 0:    -   if PDCCH contents indicate SPS release:    -   clear the configured shared uplink grant (if any).    -   else:    -   store the uplink grant and the associated HARQ information as        configured shared uplink grant;    -   initialize (if not active) or re-initialize (if already active)        the configured shared uplink grant to start in this TTI and to        recur according to semiPersistSchedIntervalUL2;    -   consider the NDI bit for the corresponding HARQ process to have        been toggled;    -   deliver the configured shared uplink grant and the associated        HARQ information to the HARQ entity for this TTI.

In a general SPS operation, the SPS C-RNTI for monitoring an SPSactivation signal is identical to the SPS C-RNTI for scrambling PUSCH.That is, UE monitors the PDCCH by using one SPS C-RNTI as a first SPSC-RNTI, and scrambles the uplink data.

In a shared SPS operation, an SPS C-RNTI for monitoring PDCCH and an SPSC-RNTI for scrambling the uplink data are separated from each other. Forexample, PDCCH is monitored by a first SPS-CRNTI and PUSCH is scrambledby a second SPS C-RNTI. Alternatively, PDCCH is monitored by a secondSPS-CRNTI and PUSCH is scrambled by a first SPS C-RNTI. These operationsare separately performed because an SPS C-RNTI for the monitoring is anidentifier which is commonly applied to a number of UE devices, and thusan eNB cannot identify, when uplink data is scrambled with the SPSC-RNTI for the monitoring, UE transmitting the uplink data.

Therefore, an SPS C-RNTI for the uplink scrambling employs a UE specificSPS C-RNTI. That is, an eNB allocates the same value to an SPS C-RNT forthe monitoring for a number of UE devices in a shared SPS. On the otherhand, the eNB allocates unique values to SPS C-RNTIs for the scramblingfor UE devices, respectively.

Scrambling PUSCH by using an SPS C-RNTI is defined in the TS 36.212 andTS 36.213.

When the UE 705 receives an uplink grant instructing the UE to initiatea general SPS operation or a shared SPS operation in operation 740, theUE initiates a general SPS operation or a shared SPS operation inoperation 745.

More specifically, when the NDI is ‘0,’ and PDCCH addressed by an SPSC-RNTI does not indicates an SPS release in operation 740, the UE 705activates an SPS for the indicated transmission resource on the PDCCHand transmits a regular BSR to the eNB.

When the eNB 710 has not received the BSR for a pre-set period of timesince the transmission of an SPS signal for the pre-scheduling, the eNBascertains that the signal is lost.

When a shared SPS is activated or deactivated to transmit a regular BSR,the present invention checks whether UE correctly receives an activation(deactivation) signal. Therefore, a condition for triggering an existingregular BSR is added as follows.

-   -   SkipUplinkTx is configured and PDCCH addressed by SPS C-RNTI        with NDI set to 0 is received, in which case the BSR is referred        below to as “Regular BSR”.

The present invention includes a new BSR trigger condition. That is,when a specified UE device is set with a shared SPS and receives PDCCHaddressed by an SPS C-RNTI where the NDI is ‘0,’ the UE transmits aregular BSR to the eNB 710. In an embodiment of the present invention,the following methods may be considered so that the eNB 710 can identifythe regular BSR transmitted as an ACK in response to the shared SPS.

1) A value of a buffer storing a BSR is set to a pre-defined value;

2) The BSR is transmitted as a truncated BSR; or

3) The BSR is transmitted in a newly defined BSR format.

Based on the methods, the BSR may have Buffer Status (BS) index valuesas in the following table. Each index value represents a range of buffersize that UE needs to use in the transmission. A specified one of thevalues may be used for only the ACK of a shared SPS as shown in TABLE 3.

TABLE 3 Index Buffer Size (BS) value [bytes] 0 BS = 0    1  0 < BS <= 102 10 < BS <= 12 3 12 < BS <= 14 4 14 < BS <= 17 5 17 < BS <= 19 6 19 <BS <= 22 7 22 < BS <= 26 8 26 < BS <= 31 9 31 < BS <= 36 10 36 < BS <=42 11 42 < BS <= 49 12 49 < BS <= 57 13 57 < BS <= 67 14 67 < BS <= 7815 78 < BS <= 91 16  91 < BS <= 107 17 107 < BS <= 125 18 125 < BS <=146 19 146 < BS <= 171 20 171 < BS <= 200 21 200 < BS <= 234 22 234 < BS<= 274 23 274 < BS <= 321 24 321 < BS <= 376 25 376 < BS <= 440 26 440 <BS <= 515 27 515 < BS <= 603 28 603 < BS <= 706 29 706 < BS <= 826 30826 < BS <= 967 31  967 < BS <= 1132 32 1132 < BS <= 1326 33 1326 < BS<= 1552 34 1552 < BS <= 1817 35 1817 < BS <= 2127 36 2127 < BS <= 249037 2490 < BS <= 2915 38 2915 < BS <= 3413 39 3413 < BS <= 3995 40 3995 <BS <= 4677 41 4677 < BS <= 5476 42 5476 < BS <= 6411 43 6411 < BS <=7505 44 7505 < BS <= 8787 45  8787 < BS <= 10287 46 10287 < BS <= 1204347 12043 < BS <= 14099 48 14099 < BS <= 16507 49 16507 < BS <= 19325 5019325 < BS <= 22624 51 22624 < BS <= 26487 52 26487 < BS <= 31009 5331009 < BS <= 36304 54 36304 < BS <= 42502 55 42502 < BS <= 49759 5649759 < BS <= 58255 57 58255 < BS <= 68201 58 68201 < BS <= 79846 5979846 < BS <= 93479 60  93479 < BS <= 109439 61 109439 < BS <= 128125 62128125 < BS <= 150000 63 BS > 150000

FIG. 8 illustrates a format of a BSR according to embodiment of thepresent invention.

The truncated BSR may have a format as follows. The format of thetruncated BSR is 1 byte in size where the first two bits indicate an LCGID value and the remaining six bits indicates a BS index value asdescribed above in the table. When the remaining size of the MAC PDU isless than 4 bytes and thus a general padding BSR does not receive a LongBSR of 4 bits, the truncated BSR is used to transmit an LCG BS indexvalue with the highest priority. The truncated BSR is identical informat to the short BSR. In an embodiment of the present invention,although the remaining size of the MAC PDU has space, when an eNBreceives a BSR of 1 bit, the eNB considers the BSR to be the ACK of ashared SPS.

It should be understood that the present invention is not limited to theBSR format shown in FIG. 8 but may define various formats of BSRaccording to design specifications.

In some embodiments of general SPS operation, a UE performs the uplinktransmission, using an SPS resource, at a cycle ofsemiPersistSchedIntervalUL (a cycle included in the SPS-config) inSpCell, based on a sub-frame initiating an SPS operation. For example,UE ascertains that the N^(th) grant has been created in a lowersub-frame of an SpCell, and performs the uplink transmission by applyinga corresponding grant to the sub-frame.

-   -   consider sequentially that the N^(th) grant occurs in the        subframe for which:

(10*SFN+subframe)=[(10*SFN_(start time)+subframe_(start time))+N*semiPersistSchedIntervalUL+Subframe_Offset*(Nmodulo 2)]modulo 10240.

Where SFN_(start time) and subframe_(start time) are the SFN andsubframe, respectively, at the time the configured uplink grant were(re-)initialised.

Although the UE does not have data to be transmitted at a correspondingtiming when transmitting an MAC PDU via the SPS resource, the UE createsand transmits a padding MAC PDU including BSR MAC CE and Padding MAC CE.The UE performs the scrambling for the uplink transmission by employinga first SPS C-RNTI.

When only MAC PDU without MAC SDU is transmitted for a number of times,implicitReleaseAfter, the UE releases the configured uplink grant.

In some embodiments of shared SPS operation, a UE performs the uplinktransmission, using a shared SPS resource, at a cycle ofsemiPersistSchedIntervalUL2 (a cycle included in the SPS-config-ext) inthe SharedSPSenabledCell, based on a sub-frame initiating an SPSoperation. For example, the UE ascertains that the N^(th) grant has beencreated in a lower sub-frame of an SpCell, and performs the uplinktransmission by applying a corresponding grant to the sub-frame.

-   -   consider sequentially that the N^(th) grant occurs in the        subframe for which:

(10*SFN+subframe)=[(10*SFN_(start time)+subframe_(start time))+N*semiPersistSchedIntervalUL2]modulo10240.

Where SFN_(start time) and subframe_(start time) are the SFN andsubframe, respectively, at the time the configured shared uplink grantwere (re-)initialised.

Referring back to FIG. 7, when the UE 705 does not have ‘data that canbe transmitted via a shared SPS transmission resource’ at acorresponding timing in transmitting MAC PDU via the SPS resource, theUE 705 does not perform the uplink transmission. When the UE 705 hastransmittable data in operation 743, the UE 705 performs the uplinktransmission in operation 744.

Although only MAC PDU without MAC SDU has been transmitted for a numberof times, implicitReleaseAfter, UE 705 does not release the configureduplink grant. The MAC PDU without MAC SDU refers to MAC PDU thatcontains only MAC CE but does not contain MAC SDU containing high layerdata.

The UE 705 performs the scrambling for the uplink transmission byemploying an SPS C-RNTI that differs from an SPS C-RNTI used to monitorPDCCH. The SPS C-RNTI applied to the scrambling may be a C-RNTI of theUE 705. That is, the identifier may be formed in various combinations asin the following table 4.

TABLE 4 Identifier for monitoring PDCCH Identifier for scrambling uplinksemiPersistSchedC-RNTI of semiPersistSchedC-RNTI2 of SPS- SPS-configconfig-ext semiPersistSchedC-RNTI2 of semiPersistSchedC-RNTI of SPS-SPS-config-ext config semiPersistSchedC-RNTI of C-RNTI allocated in theRRC SPS-config connection configuration or C- RNTI ofmobilityControlInfo

The last case is a state where SPS C-RNTI 2 is not allocated inSPS-config-ext. In this case, UE performs the scrambling for the sharedSPS uplink transmission, using the UE's C-RNTI as a UE specificidentifier.

As described above, a UE is capable of transmitting only data of alogical channel, logicalChannelIdList, via a shared SPS transmissionresource. Although UE has data of other logical channels (e.g., RRCmessages, etc.), except for the data of the logicalChannelIdList, the UEdoes not consider the data to be ‘data that can be transmitted via ashared SPS transmission resource’ but considers only data of a logicalchannel of the logicalChannelIdList to be ‘data that can be transmittedvia a shared SPS transmission resource.’

When the UE 705 receives the uplink grant indicating the SPS release inoperation 750, the UE 705 terminates the SPS operation and releases theconfigured uplink grant or the configured shared uplink grant.

More specifically, when the NDI is ‘0’ and PDCCH addressed by an SPSC-RNTI indicates the SPS release, the UE 705 deactivates the SPS for theindicated transmission resource on the PDCCH and transmits a regular BSRto the eNB 710 in operation 755.

FIG. 9 illustrates a flowchart of operations of UE according toembodiment of the present invention.

When the UE has not received valid SPS-config, or, although the UEreceived valid SPS-config, the UE has already released the SPS-config,the UE receives a control message, RRCConnectionReconfiguration, inoperation 905. The UE determines whether the control message containsSPS-config and SPS-config-ext in operation 910.

When the UE ascertains that the control message contains only SPS-configin operation 910, the UE performs operations related to a general SPS inoperation 915. When the UE ascertains that the control message containsboth SPS-config and SPS-config-ext in operation 910, the UE performsoperations related to a shared SPS in operation 920 as shown in TABLE 5.

TABLE 5 Operations related to general SPS Operations related to sharedSPS Monitor PDCCH of SpCell Monitor PDCCH of SharedSPSenabledCellDetermine whether to receive an uplink grant Determine whether toreceive an uplink grant instructing to initiate a general SPS operationinstructing to initiate operations related to a by usingsemiPersistSchedC-RNTI allocated shared SPS operation by using anidentifier in SPS-config for monitoring PDCCH Apply an SPS cycle toApply an SPS cycle to semiPersistSchedIntervalUL of SPS-configsemiPersistSchedIntervalUL2 of SPS-config-ext Scramble the transmissionof PUSCH via an Scramble the transmission of PUSCH via an SPS resource,by using SPS resource, by using an ‘identifier for‘semiPersistSchedC-RNTI allocated in uplink scrambling’ SPS-config’Transmit uplink data via PUSCH of SpCell Transmit uplink data via PUSCHof SharedSPSenabledCell Transmit padding MAC PDU when there is Omit thetransmission when there is no data no data available for transmissionavailable for transmission Release an SPS transmission resource whenMaintain an SPS transmission resource ‘MAC PDU without SDU’ issuccessively although ‘MAC PDU without SDU’ is transmitted a presetnumber of times successively transmitted a preset number of times

Alternatively, the UE may perform another operations as shown in TABLE6.

TABLE 6 Operations related to general SPS Operations related to sharedSPS Monitor PDCCH of SpCell Monitor PDCCH of SpCell Monitor DedicateSearch Space of SpCell Monitor Common Search Space of SpCell PDCCH PDCCHDetermine whether to receive uplink Determine whether to receive uplinkgrant instructing to initiate a general grant instructing to initiateoperations SPS operation by using semiPersistSchedC- related to a sharedSPS operation by using RNTI allocated in SPS-config an identifier formonitoring PDCCH The same as described above The same as described aboveThe same as described above The same as described above The same asdescribed above The same as described above The same as described aboveThe same as described above

The UE receives PDCCH instructed by an SPS C-RNTI, and determineswhether the NDI is set to ‘0’ in operation 925. The UE determineswhether the PDCCH instructs the SPS activation or deactivation (release)in operation 930.

When the UE ascertains that the PDCCH instructs the SPS activation inoperation 930, the UE activates the SPS for the transmission resourceinstructed by the PDCCH and transmits a regular BSR to the eNB inoperation 935. On the other hand, when the UE ascertains that the PDCCHinstructs the SPS deactivation in operation 930, the UE releases the SPSand transmits a regular BSR to the eNB in operation 940.

FIG. 10 illustrates a flowchart of operations of an eNB according toembodiment of the present invention.

The eNB determines to configure a shared SPS to a specified UE device inoperation 1000. The eNB transmits an RRC connection reconfigurationmessage to the UE in order to configure a shared SPS to the UE inoperation 1005. The RRC message contains information required toconfigure a shared SPS.

The eNB activates or deactivates the shared SPS by using PDCCH inoperation 1010. To this end, the PDCCH is addressed by an SPS C-RNTIwhere the NDI is a value of ‘0.’ After transmitting the PDCCH to the UE,the eNB determines whether the eNB receives a regular BSR from the UEfor a specified period of time in operation 1015.

When the eNB receives a regular BSR from the UE before a specifiedperiod of time elapses in operation 1015, the eNB considers that the UEhas successfully received the activation (deactivation) signal inoperation 1020. In order to indicate that the regular BSR has thepurpose of acknowledging failure or success of the reception ofactivation (deactivation) signal, the regular BSR may have a specifiedbuffer status (BR) index value or a truncated BSR or a new BSR formatmay be used. When the eNB has not received a regular BSR from the UE inoperation 1015, the eNB considers that the UE has not activated ordeactivated a shared SPS in operation 1025.

In some embodiments, an eNB enables to use a regular BSR on the uplinkin order to determine whether UE has correctly received an activation(deactivation) signal of a shared SPS.

In some embodiments, a new MAC CE to comply with the purpose describedabove is defined. For example, a newly defined MAC CE may be assigned anew uplink LCD that differs from that allocated to an existing MAC CE.The newly defined MAC CE has a sub-header containing the LCD, but doesnot have an MAC CE in the MAC payload of the MAC PDU (zero bits).

The eNB transmits PDCCH to activate or deactivate a shared SPS, and thendetermines whether the LCID is contained in the sub-header of thespecified MAC PDU for a specified period of time, x. When the eNBascertains that the LCID is contained in the sub-header of the specifiedMAC PDU, the eNB considers that the UE has successfully received thePDCCH.

As described above, Aforementioned embodiments are capable of increasingthe reliability of an activation/release signal of the SPS forprescheduling during the latency reduction SI

In some embodiments, a regular BSR is triggered when anactivation/release signal of the SPS for prescheduling is received.

A buffer status report (BSR) may be triggered if any of the followingevents occur:

-   -   UL data, for a logical channel which belongs to an LCG, becomes        available for transmission in the RLC entity or in the PDCP        entity and either the data belongs to a logical channel with        higher priority than the priorities of the logical channels        which belong to any LCG and for which data is already available        for transmission, or there is no data available for transmission        for any of the logical channels which belong to an LCG, in which        case the BSR is referred below to as “Regular BSR”;    -   UL resources are allocated and number of padding bits is equal        to or larger than the size of the buffer status report MAC        control element and a subheader, in which case the BSR is        referred below to as “Padding BSR”;    -   retxBSR-Timer expires and the MAC entity has data available for        transmission for any of the logical channels which belong to a        LCG, in which case the BSR is referred below to as “Regular        BSR”;    -   periodicBSR-Timer expires, in which case the BSR is referred        below to as “Periodic BSR”.    -   SkipUplinkTx is configured and PDCCH addressed by SPS C-RNTI        with NDI set to 0 is received, in which case the BSR is referred        below to as “Regular BSR”.

When an eNB has not received a BSR for a preset period of time since thetransmission of a signal for the SPS for pre-scheduling, the eNBascertains that the signal is lost.

The aforementioned embodiments of the present invention operate asfollows.

Configure RRC connection with eNB;

Receive an RRC connection reconfiguration message from an eENB;

SPS configuration information;

Pre-scheduling indicator;

Monitor SPS C-RNTI in a serving cell;

Receive NDI=0 and PDCCH addressed by SPS C-RNTI; and the SPS release isnot indicated;

Activate an SPS for an indicated transmission resource on the PDCCH andtrigger a regular BSR;

Transmit data using the SPS resource;

Transmit transmittable data except for a padding BSR; otherwise, omitthe transmission;

Receive NDI=0 and PDCCH addressed by an SPS C-RNTI; and the SPS releaseis not indicated;

Replace an existing SPS transmission resource with the newly indicatedtransmission resource and trigger a regular BSR;

Transmit data using the SPS resource;

Receive NDI=0 and PDCCH addressed by an SPS C-RNTI; and the SPS releaseis indicated; and

Releases the SPS transmission resource and trigger a regular BSR.

In some embodiments, a BRS is a regular BSR for the SPS ACK; e.g., BS isset to a specified value; a truncated BSR is transmitted; a new BSRformat is defined, etc.

In aforementioned embodiments, the cell selection and re-selection usinga number of PMAX parameters are effectively performed.

In aforementioned embodiments, the reliability of a semi-persistentscheduling (SPS) activation signal and an SPS deactivation signal in theshared SPS operation are increased.

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims.

What is claimed is:
 1. A method performed by a terminal in a wireless communication system, the method comprising: receiving, from a base station, a system information block (SIB) including first maximum power information and at least one second maximum power information; obtaining a first maximum transmission power level for a cell based on the first maximum power information and a second maximum transmission power level for the cell based on one from the at least one second maximum power information; identifying a compensation parameter (P_(compensation)) associated with a cell selection reception level value (Srxlev) based on the first maximum transmission power level and the second maximum transmission power level; identifying the Srxlev for the cell based on the P_(compensation); and performing a cell selection for the cell, based on the identified Srxlev, wherein the by: P_(compensation) is identified P _(compensation)=max(P _(EMAX1) −P _(PowerClass),0)−(min(P _(EMAX2) ,P _(PowerClass))−min(P _(EMAX1) ,P _(PowerClass))), where the P_(EMAX1) is the first maximum transmission power level, P_(EMAX2) is the second maximum transmission power level, and the P_(Powerclass) is a maximum radio frequency output power of the terminal.
 2. The method of claim 1, wherein the Srxlev is identified by subtracting a minimum required reception level in the cell (Q_(rxlevmin)), an offset to the Q_(rxlevmin) (Q_(rxlevminoffset)), and the P_(compensation) from a measured cell reception level value (Q_(rxlevmeas)).
 3. The method of claim 2, wherein the cell selection is performed as a result of a periodic search for a higher priority public land mobile network (PLMN) while camped on a visited PLM N (VPLMN).
 4. The method of claim 3, wherein the cell selection for the cell is performed, in case that the identified Srxlev for the cell is larger than 0 and a cell selection quality value (Squal) for the cell is larger than
 0. 5. A method performed by a base station in a wireless communication system, the method comprising: generating first maximum power information and at least one second maximum power information; and transmitting, to a terminal, a system information block (SIB) including the first maximum power information and the at least one second maximum power information, wherein a first maximum transmission power level for a cell is obtained based on the first maximum power information, and a second maximum transmission power level for the cell is obtained based on one from the at least one second maximum power information, wherein a compensation parameter (P_(compensation)) associated with a cell selection reception level value (Srxlev) is identified based on the first maximum transmission power level and the second maximum transmission power level, wherein the Srxlev for the cell is identified based on the P_(compensation), wherein a cell selection for the cell is performed based on the identified Srxlev, and wherein the by: P_(compensation) is identified P _(compensation)=max(P _(EMAX1) −P _(PowerClass),0)−(min(P _(EMAX2) ,P _(PowerClass))−min(P _(EMAX1) ,P _(PowerClass))), where the P_(EMAX1) is the first maximum transmission power level, P_(EMAX2) is the second maximum transmission power level, and the P_(Powerclass) is a maximum radio frequency output power of the terminal.
 6. The method of claim 5, wherein the Srxlev is identified by subtracting a minimum required reception level in the cell (Q_(rxlevmin)), an offset to the Q_(rxlevmin) (Q_(rxlevminoffset)), and the P_(compensation) from a measured cell reception level value (Q_(rxlevmeas)).
 7. The method of claim 6, wherein the cell selection is performed as a result of a periodic search for a higher priority public land mobile network (PLMN) while camped on a visited PLM N (VPLMN).
 8. The method of claim 7, wherein the cell selection for the cell is performed, in case that the identified Srxlev for the cell is larger than 0 and a cell selection quality value (Squal) for the cell is larger than
 0. 9. A terminal in a wireless communication system, the terminal comprising: a transceiver configured to transmit and receive a signal; and a controller configured to: receive, from a base station, a system information block (SIB) including first maximum power information and at least one second maximum power information, obtain a first maximum transmission power level for a cell based on the first maximum power information and a second maximum transmission power level for the cell based on one from the at least one second maximum power information, identify a compensation parameter (P_(compensation)) associated with a cell selection reception level value (Srxlev) based on the first maximum transmission power level and the second maxim um transmission power level, identify the Srxlev for the cell based on the P_(compensation), and perform a cell selection for the cell, based on the identified Srxlev, wherein the by: P_(compensation) is identified P _(compensation)=max(P _(EMAX1) −P _(PowerClass),0)−(min(P _(EMAX2) ,P _(PowerClass))−min(P _(EMAX1) ,P _(PowerClass))), where the P_(EMAX1) is the first maximum transmission power level, P_(EMAX2) is the second maximum transmission power level, and the P_(Powerclass) is a maximum radio frequency output power of the terminal.
 10. The terminal of claim 9, wherein the Srxlev is identified by subtracting a minimum required reception level in the cell (Q_(rxlevmin)), an offset to the Q_(rxlevmin) (Q_(rxlevminoffset)), and the P_(compensation) from a measured cell reception level value (Q_(rxlevmeas)).
 11. The terminal of claim 10, wherein the cell selection is performed as a result of a periodic search for a higher priority public land mobile network (PLMN) while camped on a visited P LMN (VPLMN).
 12. The terminal of claim 11, wherein the cell selection for the cell is performed, in case that the identified Srxlev for the cell is larger than 0 and a cell selection quality value (Squal) for the cell is larger than
 0. 13. A base station in a wireless communication system, the base station comprising: a transceiver configured to transmit and receive a signal; and a controller configured to: generate first maximum power information and at least one second maximum power information, and transmit, to a terminal, a system information block (SIB) including the first maximum power information and the at least one second maximum power information, wherein a first maximum transmission power level for a cell is obtained based on the first maximum power information, and a second maximum transmission power level for the cell is obtained based on one from the at least one second maximum power information, wherein a compensation parameter (P_(compensation)) associated with a cell selection reception level value (Srxlev) is identified based on the first maximum transmission power level and the second maximum transmission power level, wherein the Srxlev for the cell is identified based on the P_(compensation), wherein a cell selection for the cell is performed based on the identified Srxlev, and wherein the P_(compensation) is identified by: P _(compensation)=max(P _(EMAX1) −P _(PowerClass),0)−(min(P _(EMAX2) ,P _(PowerClass))−min(P _(EMAX1) ,P _(PowerClass))), where the P_(EMAX1) is the first maximum transmission power level, P_(EMAX2) is the second maximum transmission power level, and the P_(Powerclass) is a maximum radio frequency output power of the terminal.
 14. The base station of claim 13, wherein the Srxlev is identified by subtracting a minimum required reception level in the cell (Q_(rxlevmin)), an offset to the Q_(rxlevmin) (Q_(rxlevminoffset)), and the P_(compensation) from a measured cell reception level value (Q_(rxlevmeas)).
 15. The base station of claim 14, wherein the cell selection is performed as a result of a periodic search for a higher priority public land mobile network (PLMN) while camped on a visited PLMN (VPLMN).
 16. The base station of claim 15, wherein the cell selection for the cell is performed, in case that the identified Srxlev for the cell is larger than 0 and a cell selection quality value (Squal) for the cell is larger than
 0. 